1. Field of the Invention
The present invention relates to a radiation sensitive resin composition, a method for forming a pattern, a polymer and a compound.
2. Discussion of the Background
Miniaturization of various types of electronic device structure such as semiconductor devices and liquid crystal devices has been accompanied by demands for miniaturization of resist patterns in lithography processes. Although fine resist patterns having a line width of about 90 nm can be formed using, for example, ArF excimer laser at present, future finer pattern formation is required.
In such pattern formation, a chemically amplified resin composition has been conventionally used extensively. The chemically amplified resin composition contains an acid generating component that generated an acid upon exposure, and a resin component whose solubility in developer solutions varies by the action of this acid (see Japanese Unexamined Patent Application, Publication No. S59-45439), whereby a pattern can be formed using the difference of rates of dissolution between a site exposed with light and a sites unexposed with light.
On the other hand, a liquid immersion lithography technique was developed for resist pattern formation. It is reported that high resolving abilities can be attained according to the liquid immersion lithography, even if a light source of the same exposure wavelength is employed, similarly to the case in which a light source of a shorter wavelength is employed in conventional resist pattern formation. Thus, liquid immersion lithography has drawn attention as a technique that achieves high resolution in manufacturing semiconductor elements which require a large amount of investment in equipment while suppressing increase in costs. As a resin composition suited for the liquid immersion lithography, in attempts to be capable of inhibiting elution of an acid generator and the like from a resist film to a liquid for liquid immersion lithography, and improving water break of the resist film, and the like, a resin composition was proposed which contains a highly hydrophobic polymer including fluorine atoms (see PCT International Publication No. 2007/116664).
Resin compositions that are hydrophobic during liquid immersion lithography but the hydrophobicity decreases upon development with alkali were proposed. For example, a resin composition containing a polymer including fluorine atoms that has an acid-dissociable bivalent linking group, and an alkali-dissociable group has been known (see Japanese Unexamined Patent Application, Publication No. 2010-020284). In addition, a resin composition in which a polymer having an alkali-dissociable group and a fluorocarboxylic acid structure is used as a water repellent resin has been known (see Japanese Unexamined Patent Application, Publication No. 2010-210953).